Micro-CT Scanning to Examine Soil Clogging Behavior of Natural Fiber Drains

The use of jute and coir fibers as natural fiber drains to facilitate drainage and soft soil stabilization has been proposed for decades. However, their uncertain hydraulic behavior has often hampered their wider application in major infrastructure projects. Because these drains have a complex porous structure that can trap soil particles and reduce their discharge capacity, a comprehensive laboratory investigation in which soft soil was used to interact with different fiber drains under varying confining pressure was conducted via a discharge capacity test scheme. Nondestructive micro–computed tomography (CT) scanning followed by a series of image processing techniques was applied to the drains to capture their three-dimensional porous characteristics, which were then used to clarify their hydraulic behavior. The study revealed that there are two major types of components—intra- and interbundle voids—making porosity in a fiber drain, and they can be used to evaluate the drain discharge capacity. The larger the interbundle porosity, the higher the drain discharge capacity. Jute filters not only enlarge the interbundle porosity but also—if they are thick enough—help drains resist undue lateral pressure and clogging. Fiber drains are more sensitive to confinement than polymeric drains, because their discharge capacity decreases considerably at higher confining pressures. This study enables the hydraulic properties of natural fiber drains subjected to soil clogging to be properly understood so that drain designs can be optimized to make them more competitive with conventional polymeric drains.